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Universal::errno cpan:GARLANDG last updated on 2020-11-14



Universal::errno - Wrapper for errno modules for Unix and Windows


use Universal::errno;


  say errno;
  say "failed: {errno}";
  say +errno;              #2


Universal::errno is an extension of and wrapper around lizmat's Unix::errno, and exports the same errno and set_errno interface. It works on Linux, Windows, and Macos. BSD support is untested, but should work.

One added feature is the strerror method, which gets the string for the error in a thread-safe way. On platforms that support it, it uses POSIX strerror_l. This allows getting the error string that corresponds to the user's set locale. On platforms that don't support it, strerror_r (XSI) is used. On Windows, this is done using GetLastError() and FormatMessageW. Windows also has a SetLastError function which is used instead of masking the value.

This module provides an Exception class, X::errno. To check the type of error in a portable way, use the symbol method and smartmatch against an entry in the Errno enum.

It also provides a trait: error-model. Mark a sub or method with is error-model and the trait will automatically box the errno for you and reset errno to 0.

For calls that return -errno, there is also a trait error-model.

As an example of a real-world scenario, this code sets up a socket using socket(2) and handles the errors with a CATCH block.

use NativeCall;
sub socket(int32, int32, int32) returns int32 is native is error-model<errno> { ... }
my int32 $socket;

try {
  $socket = socket(AF::INET, SOCK_DGRAM, 0);
    when X::errno {
      given .symbol {
        when Errno::EINVAL {
          die "Invalid socket type"
        when Errno::EACCES {
          die "Permission denied"


Travis Gibson [email protected]


Uses a heavily-modified Unix::errno module for Unix-like OSes, and uses Windows::errno (also based on lizmat's Unix::errno) for Windows OSes.

Universal::errno::Unix contains all of the modified code, and this README also borrows the SYNOPSIS example above. The original README and COPYRIGHT information for lizmat's Unix::errno has been preserved in Universal::errno::Unix.

lizmat's Unix::errno can be found at


Copyright 2020 Travis Gibson

This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.